Practical dosing of propofol in morbidly obese patients

Relationship between preinduction electroencephalogram patterns and propofol sensitivity in adult patients

PURPOSE

To determine the precise induction dose, an objective assessment of individual propofol sensitivity is necessary. This study aimed to investigate whether preinduction electroencephalogram (EEG) data are useful in determining the optimal propofol dose for the induction of general anesthesia in healthy adult patients.

METHODS

Seventy healthy adult patients underwent total intravenous anesthesia (TIVA), and the effect-site target concentration of propofol was observed to measure each individual's propofol requirements for loss of responsiveness. We analyzed preinduction EEG data to assess its relationship with propofol requirements and conducted multiple regression analyses considering various patient-related factors.

RESULTS

Patients with higher relative delta power (ρ = 0.47, p < 0.01) and higher absolute delta power (ρ = 0.34, p = 0.01) required a greater amount of propofol for anesthesia induction. In contrast, patients with higher relative beta power (ρ = -0.33, p < 0.01) required less propofol to achieve unresponsiveness. Multiple regression analysis revealed an independent association between relative delta power and propofol requirements.

CONCLUSION

Preinduction EEG, particularly relative delta power, is associated with propofol requirements during the induction of general anesthesia. The utilization of preinduction EEG data may improve the precision of induction dose selection for individuals.

Remimazolam Induction in a Patient with Super-Super Obesity and Obstructive Sleep Apnea: A Case Report

Background: With the rising prevalence of obesity, anesthesiologists are expected to increasingly encounter patients with obesity, which poses challenges for anesthetic management. The use of remimazolam, an intravenous anesthetic agent approved in 2020, may be beneficial in these patients. However, its use in patients with super-super obesity remains underexplored. Case Description: A 55-year-old woman with a body mass index (BMI) of 60.6 kg/m² and moderate obstructive sleep apnea (OSA) underwent laparoscopic sleeve gastrectomy under general anesthesia. The transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) technique was used along with the administration of remimazolam at a rate of 6 mg/kg/h based on the total body weight. The patient was sedated within 125 s without any signs of hemodynamic instability, and the surgery was completed successfully. Conclusions: This case study demonstrates the potential effectiveness of remimazolam infusion for inducing general anesthesia in patients with super-super obesity. The infusion rate, derived from the total body weight, yielded an outcome comparable with that observed in individuals without obesity. Further studies with larger cohorts are required to confirm these findings.

Optimizing Robotic Hysterectomy for the Patient Who Is Morbidly Obese with a Surgical Safety Pathway

STUDY OBJECTIVE

Obesity is a growing worldwide epidemic, and patients classified as obese undergoing gynecologic robotic surgery are at increased risk for surgical complications. This study aimed to evaluate the feasibility and outcomes of a surgical safety protocol known as the High BMI [Body Mass Index] Pathway (HBP) for patients with BMI ≥40 kg/m² undergoing planned robotic hysterectomy. Our primary outcome was the rate of all-cause perioperative complications in patients undergoing surgery with the use of the HBP.

DESIGN

A retrospective cohort study.

SETTING

An academic teaching hospital.

PATIENTS

A total of 138 patients classified as morbidly obese (BMI ≥40 kg/m²) undergoing robotic hysterectomy.

INTERVENTIONS

The HBP was developed by a multidisciplinary team and was instituted on January 1, 2016, as a quality improvement project. Patients classified as morbidly obese undergoing robotic hysterectomy after this date were compared with consecutive historical controls.

MEASUREMENTS AND MAIN RESULTS

Seventy-two patients underwent robotic hysterectomies on the HBP and were compared with 66 controls. There were no differences in age, BMI, blood loss, number of comorbidities, or cancer diagnosis. Since the implementation of the HBP, there has been a decrease in anesthesia time (-57.0 minutes; p = .001) and total operating room time (-47.0 min; p = .020), as well as lower estimated blood loss (median 150 mL [interquartile range 100-200] vs 200 mL [interquartile range 100-300]; p = .002) and reduction in overnight hospital admissions (33.3% vs 63.6%; p <.001). In the HBP group, there were fewer all-cause complications (19.4% vs 37.9%; p = .023) and infectious complications (8.3% vs 33.3%; p = .001), and there was no increase in the readmission rates (p = .400). In multivariable analysis, the HBP reduced all-cause complications (odds ratio 0.353; p = .010) after controlling for the covariate (total time in the operating room).

CONCLUSION

The HBP is a feasible method of optimizing the outcome for patients classified as morbidly obese undergoing major gynecologic surgery. Initiation of the HBP can lead to decreased anesthesia and operating times, all-cause complications, and overnight hospital admissions without increasing readmission rates.

Recent advances in anesthesia of the obese patient

The anesthetic management of an obese patient can be challenging because of the altered anatomy and physiology associated with obesity. In this article, I review the recent medical literature and highlight some of the controversies in the airway management and drug dosing of morbidly obese patients.

Characterization of cardiovascular depression effect for propofol during anesthesia induction period on morbidly obese patients

This study aims to determine the pharmacodynamics (PD) effect (measured by cardiovascular depression) of propofol during anesthesia induction period on morbidly obese (MO) patients. Four hemodynamics indexes [i.e., three indexes about blood pressure and cardiac output (CO)] representing cardiovascular function were measured. Pharmacokinetic/pharmacodynamic (PK/PD) modeling was performed by population analysis to obtain PD parameters. Two propofol dosing scalars, namely, dosing based on total body weight (TBW) or lean body weight (LBW), were used for MO subjects. The PD data were well described by a PK/PD model. Blood pressure and CO were rapidly decreased within one minute after intravenous injection of propofol (2 mg/kg). TBW group showed significantly lower blood pressure and CO values at and 1 min after propofol administration compared with the control group, whereas the control and LBW groups had similar PD profiles. In addition, the propofol EC₅₀ value was significantly decreased in MO patients, whereas all other PD parameters were similar between control and MO subjects. This change indicated that propofol potency and/or sensitivity was increased in MO subjects. For MO patients, dosing of propofol based on LBW rather than TBW would be a safer choice due to a less cardiovascular depression effect.